A bone marrow biopsy is a test performed by a physician to evaluate bone marrow function. Bone marrow produces red blood cells, white blood cells, and platelets. This test allows the doctor to study these cells in the various stages of development to better plan treatment of bone disease.
The physician may recommend blood tests or special imaging tests such as a bone scan, a CT (or CAT) scan, an MRI, or an angiogram to ascertain the need for intervention into the bone marrow space. A biopsy may be prescribed to remove blood and fluid aspirates from the marrow space as well as a core sample of the bone marrow to determine whether cancer or other disease is present.
In the procedure, two types of samples are required for a full diagnosis. Fluid or aspirate must be drawn from the marrow cavity for cytological study and a core sample of marrow material must be obtained for histological study.
In the conventional prior art procedure, the physician penetrates the hard bone of the patient with a series of different needles from a bone marrow biopsy set. The first needle used is a small bore needle designed to aspirate fluid for cytological study. The small bore needle is twisted down through the cortex of the bone into the marrow space. Once the marrow cavity is accessed, the stylet of the small bore needle is removed and a syringe is attached to the opening where the stylet resides. A fluid sample is withdrawn from the marrow space using the syringe attached to the needle. The bore of the needle used to aspirate fluid must be small so that the small amount of fluid that is available can be drawn up the needle into the syringe. If the needle is too large in internal diameter, there is not enough fluid available to fill the internal volume of the bore and still have enough aspirate fluid available to reach up the full length of the needle and to fill the syringe.
After this aspirated fluid is removed, a second hole must be created in the cortex to obtain a solid marrow sample or core. This second hole is required because the act of aspirating fluid from the marrow dries out the marrow in that area making it unsuitable to obtain a satisfactory marrow core sample.
A large bore needle is used to create this second hole. This larger bore needle is designed with a cylindrical body of a first diameter, tapering to a distal end of a second diameter. The needle is tapered in the last 2 to 3 centimeters of the distal end to a smaller sharpened opening with a cutting edge. This reduced second diameter of the large bore needle assists in capturing and holding the core sample as it is removed from the patient.
Once the hard bone is penetrated, by the large bore needle, the stylet of the needle is removed and the hollow cannula of this second needle is driven into the marrow space to obtain a solid core of marrow. The large bore needle is removed from the patient and the marrow sample is removed. This second needle has a much larger internal bore than the needle used to aspirate, so that the marrow can easily be cored and removed from the marrow cavity.
A bone marrow surgical needle is disclosed in U.S. Pat. No. 5,012,818 to Joishy. Joishy discloses a biopsy needle with a tubular outer sleeve in which two separate conduits are contained. The first conduit is used to obtain the solid bone biopsy sample. The second conduit is used to obtain the fluid bone marrow biopsy sample. Each conduit contains two removable stylets. The handle of the Joishy needle can be opened to remove the stylets from each conduit and attach a syringe to aspirate the bone marrow biopsy sample. The needle is tapered at the cutting end to assist in breaking off and retaining the bone biopsy sample. During use, the needle is pushed into the bone and the handle of the biopsy needle is opened. The first stylet is then removed thereby leaving an opening in the first conduit to receive a solid bone biopsy sample and the handle is again closed. The needle is then pushed further into the bone and the hard bone biopsy sample enters the first conduit. The handle is again opened and the second stylet is removed from the second conduit. A syringe is attached to second conduit at the handle and the bone marrow biopsy sample is aspirated through the second conduit and into the syringe. The needle is then manipulated to assist in breaking off the bone biopsy sample and then removed from the subject.
The Joishy needle requires a sleeve with two conduits and two removable stylets within the conduits. The biopsy procedure requires multiple steps to perform and therefore can be time-consuming. Also, the manufacture of such a complex needle can be difficult and costly.
U.S. Pat. No. 6,007,496 issued Dec. 28, 1999 to Brannon describes a device for harvesting bone, including a hollow cylindrical rod having a sharpened distal end, a proximal end with a handle thereon, and a chamber therein extending axially between the proximal and distal ends. A plunger rod is inserted into the proximal end of the cylindrical rod, the plunger rod being slidable axially within the chamber. A sealing support is provided on the proximal end of the hollow cylindrical rod for engaging the plunger rod to establish a slidable hermetic seal therebetween and prevent retrograde flow of air into the chamber from the proximal end of the cylindrical rod. The sleeve also includes a side opening in the cylindrical rod communicating with the chamber, which is connectable to a source of vacuum for evacuating fluid from the chamber into a fluid reservoir connectable to the side opening for collecting fluid therein. The plunger rod must be constantly advanced to compensate for pressure drop due to collapse of the collected sample at the distal end of the cannula.
U.S. Pat. No. 6,022,324 issued Feb. 8, 2000 to Skinner shows a biopsy instrument, which can be used to take a bone biopsy sample or a soft tissue biopsy sample. The biopsy instrument includes a biopsy needle and a biopsy gun. In operation, a triggering mechanism actuates a firing mechanism causing the cradle together with the needle and the attached syringe to fire forward with a sufficient force such that the needle penetrates the target tissue organ causing a first tissue sample to be cored in the needle. The disposable syringe can then be used to obtain a second tissue sample up through the biopsy needle using a vacuum created in the disposable syringe when the plunger is maintained in a rearward position while the syringe fires forward. In a bone biopsy procedure, the first tissue sample is a bone sample and the second tissue sample is a liquid bone marrow sample. The entire bore of the core sample needle is used to aspirate the fluid sample, which may not be sufficient to fill the needle bore for the full length of the needle.
Skinner employs a retainer projecting into the cannula bore from its larger diameter to retain the cored hard biopsy sample. The sample has a smaller cross-sectional area equal to that of the tapered distal end of the cannula.
It would be desirable to have an improved needle assembly requiring only one entry site into the bone that allows aspirated fluid to be drawn in a sufficient amount for cytological study from the areas adjacent the sides of the needle without disturbing the marrow directly in front of and below the needle tip and that allows the same needle to core the undisturbed marrow in a sufficient amount for histological study from the same needle assembly.
Accordingly, one object of the present invention is to provide an improved needle assembly that requires only one entry site into the bone to obtain aspirate fluid and bone marrow core sample.
Another object of the invention is to provide an improved needle assembly that allows aspirated fluid to be drawn from the areas adjacent to the sides of the needle and allows the same needle to core the undisturbed marrow directly in front of and below the needle tip.